U.S. patent number 4,211,466 [Application Number 05/962,736] was granted by the patent office on 1980-07-08 for crimped electrical connections for conductors on thin substrates.
This patent grant is currently assigned to AMP Incorporated. Invention is credited to Charles E. Reynolds.
United States Patent |
4,211,466 |
Reynolds |
July 8, 1980 |
Crimped electrical connections for conductors on thin
substrates
Abstract
Electrical connections for conductors on two spaced apart films
are provided by means of a strip of connecting devices. The strip
comprises a carrier strip with the connecting devices extending
therefrom at spaced intervals. Each connecting device has first and
second side-by-side crimp portions, each crimp portion being
generally U-shaped. The connecting devices are crimped onto the two
films by positioning one film between the arms of the first
connecting devices of a section of the strip and the second film
between the arms of the second connecting devices. The connecting
devices are then crimped onto the film and the carrier strip is
removed. A housing for the connecting devices is also
disclosed.
Inventors: |
Reynolds; Charles E.
(Mechanicsburg, PA) |
Assignee: |
AMP Incorporated (Harrisburg,
PA)
|
Family
ID: |
25506280 |
Appl.
No.: |
05/962,736 |
Filed: |
November 21, 1978 |
Current U.S.
Class: |
439/499; 439/329;
439/422; 439/596; 439/77; 439/885 |
Current CPC
Class: |
H05K
3/326 (20130101); H01R 12/79 (20130101); H01H
2207/036 (20130101); H01R 13/501 (20130101) |
Current International
Class: |
H01R
12/00 (20060101); H05K 3/32 (20060101); H01R
12/24 (20060101); H01R 13/50 (20060101); H01R
013/54 (); H05R 001/12 () |
Field of
Search: |
;339/17F,176MF,98,99,97R,97C,21R,21M,276SF ;200/5A |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Fold Switch, R. H. Harris, IBM Technical Disclosure Bulletin, vol.
19, No. 10 (Mar. 1977) p. 3815. _.
|
Primary Examiner: Lake; Roy
Assistant Examiner: Desmond; Eugene F.
Attorney, Agent or Firm: Raring; Frederick W.
Claims
I claim:
1. The combination of first and second insulating films having
conductors thereon and electrical connecting devices crimped onto
said films, said films having parallel spaced-apart edges, said
conductors extending to said edges, said conductors on said first
film being laterally offset from said conductors on said second
film, said electrical connecting devices being characterized in
that:
each of said connecting devices comprises two crimped portions,
each of said crimped portions comprising opposed cantilever beams
connected to each other by an arcuate bight portion, said two
crimped portions being in side-by-side relationship and being
connected to each other at the outer ends of the cantilever beams
of the two crimped portions which are adjacent to each other,
said first film being between said cantilever beams of one of said
crimped portions of each of said crimped connecting devices with
said edge of said first film adjacent to said bight portion and
with one of said conductors of said first film against one of said
cantilever beams of said one crimped portion, said second film
being between said cantilever beams of the other one of said
crimped portions of each of said crimped connecting devices with
said edge of said second film adjacent to said bight portion and
with one of said conductors of said second film against one of said
cantilever beams of said other crimped portion,
said cantilever beams of each crimped portion being resiliently
flexed against said films and being maintained in a flexed
condition by said bight portions whereby,
said films are clamped between said cantilever beams of said
crimped portions and said cantilever beams are resiliently
maintained against, and in electrical contact with, said conductors
and each of said conductors is in electrical contact with one of
said electrical connecting devices.
2. The combination set forth in claim 1, each of said connecting
devices having a contact means integral therewith and extending
therefrom.
3. The combination set forth in claim 2, each of said contact means
comprising a contact member extending laterally from the free end
of one of said cantilever beams.
4. The combination set forth in either of claims 2 or 3 and
insulating enclosing means, said enclosing means being in enclosing
relationship to portions of said films and portions of said
connecting devices.
5. The combination set forth in claim 4, said contact means
extending externally of said enclosing means.
6. The combination set forth in claim 4, said enclosing means
comprising a rigid molded housing.
7. The combination set forth in claim 2, and a rigid molded housing
means, said housing means comprising folded sections, said portions
of said films and said connecting devices being between said folded
sections, said contact means extending externally of said housing
means.
8. The combination set forth in claim 7, said contact means
comprising contact pins, said contact pins extending through
openings in one of said sections.
9. A continuous strip of stamped and formed electrical connecting
devices which are intended to be crimped onto spaced apart
conductors on first and second insulating films, said conductors on
each film being spaced apart by a distance 2D, said films being in
parallel planes with the conductors on said first film offset from
the conductors on the second film, said strip comprising:
a continuous carrier strip, said connecting devices being integral
with said carrier strip and being spaced-apart by a distance D,
each of said connecting devices comprising first and second crimp
portions, each of said crimp portions being generally U-shaped and
comprising a bight and cantilever beams extending from said bight,
one of said cantilever beams of said first crimp portion being
integral with said carrier strip at its end, the other cantilever
beam of said first crimp portion being integral at its end with one
cantilever beam of said second crimp portion whereby,
upon positioning said first film between said cantilever beams of
said first crimp portions of said connecting devices on a section
of said strip, positioning said second film between said cantilever
beams of said second crimp portions of said connecting devices on
said section of said strip with each of said connecting devices in
alignment with one of said conductors, and upon thereafter crimping
said connecting devices onto said films and removing said carrier
strip from said connecting devices, an individual connecting device
will be crimped onto each of said conductors.
10. A continuous strip of stamped and formed connecting devices as
set forth in claim 9, each of said connecting devices having a
contact portion extending therefrom which is dimensioned to be
mated with a further conductor.
11. A continuous strip of stamped and formed connecting devices as
set forth in claim 10, each of said contact portions comprising a
contact post.
Description
DESCRIPTION
1. Technical Field of the Invention
This invention relates to crimped electrical connections for films
in parallel spaced-apart relationship. The disclosed embodiment
relates to connections for conductors on the films of a membrane
switch.
2. Background of the Invention
Application Ser. No. 960,425 filed Nov. 13, 1978 discloses and
claims an improved crimped connection for conductors on substrates
such as relatively thin films. The conductors may be produced on
the films by silkscreening, by electrodeposition, or by etching a
laminate comprising a substrate and a sheet of conductive metal to
leave the desired conductive paths. In accordance with the
teachings of the above identified application, a sheet metal
U-shaped device is provided and the edge of the film is positioned
between the cantilever beams of the connecting device with the
conductor in alignment with one of the cantilever beams. The
connecting device is then crimped onto the film by applying
diametrically opposite crimping forces to the ends of the
cantilever beam until the sides of the beams are against the film.
Thereafter, the bight portion of the connecting device is
plastically deformed and the cantilever beams are flexed so that in
the finished crimped section, they are biased against the film and
one of the beams is maintained in electrical contact with the
conductor.
Application Ser. No. 790,635 now U.S. Pat. No. 4,143,253, issued
Mar. 6, 1979 discloses a membrane switch comprising two
spaced-apart films which are separated by a separator film having
openings therein at predetermined locations. Conductors are
provided on the surfaces of the outside films so that when the
switch is pressed at the location of one of the openings,
conductors on the outside films will be contacted with each other.
The outside films have tail portions which extend beyond the
separator film and the conductors extend across the opposed
surfaces of the tail portions. Electrical connections are required
for the conductors on these tail portions to connect the switch
conductors to further circuitry.
The present invention is directed to the achievement of electrical
connections to conductors on spaced-apart films with the
connections being of the type disclosed and claimed in the above
identified Application Ser. No. 960,425.
In accordance with the practice of the present invention, a strip
of connecting devices is provided having a carrier strip with the
individual connecting devices extending therefrom at spaced
intervals. Each connecting device has two crimp portions, each of
which is generally U-shaped. The crimp portions are connected at
the ends of their adjacent arms and a terminal pin or the like,
extends from the free arms of the crimp portion which is remote
from the carrier strip. In use, one of the films from the switch is
located beween the arms of one of the crimp portions of a strip of
terminals and the other film is located between the arms of the
other crimp portions of the terminals of the strip. The crimp
portions are crimped onto the two films in accordance with the
teachings of application Ser. No. 960,425 and the carrier strip is
removed so that each conductor is connected to one connecting
device. A suitable housing for the tail portion of the strip can
also be provided.
DESCRIPTION OF THE DRAWING FIGURES:
FIG. 1 is a fragmentary perspective view of a portion of a strip of
connecting devices in alignment with two spaced-apart insulating
films having conductors on their opposed surfaces, these films
forming part of a switch device shown in FIG. 6.
FIG. 2 is a sectional side view of a pair of crimping dies for
crimping an individual connecting device onto two spaced-apart
films, this view showing the position of the crimping dies prior to
the beginning of the crimping operation.
FIG. 3 is a view similar to FIG. 2 but showing the positions of the
parts at the end of the crimping operation.
FIG. 4 is a sectional side view of a crimped connecting device
illustrating the removal of a carrier strip.
FIG. 5 is a fragmentary view showing connecting devices crimped
onto the conductors of the film with the connecting devices in
alignment with a connector housing.
FIG. 6 is a view illustrating the assembly of the connector housing
to the films.
FIG. 7 is a cross-sectional view of the connector housing assembled
to the connecting devices and the two films and illustrating the
manner in which the crimped connecting devices are mated with a
further connecting device on a circuit board.
PRACTICE OF THE INVENTION:
FIGS. 1-7 show an embodiment of the invention which serves to
connect conductors 6, 8 on the opposed surfaces of spaced-apart
parallel films 10, 12 to conductors 26 (FIG. 7) on the underside 28
of a circuit board 30. The connecting devices 4 are produced as a
continuous strip 2 and are crimped en masse onto the conductors 6,
8 and later assembled to a housing 60. The films 10, 12 are part of
the tail portion 14 of a switch 16, FIG. 6, and the conductors 6, 8
extend to switch conductors 18, 20 on the films. These switch
conductors extend transversely of each other in the switch portion
16. The two films are separated by, and bonded to, a separator film
22 which has circular holes 24 therein at the locations of the
crossing points of the conductors 20, 18. When the surface of the
film 10 is pressed at one of the openings 24, the conductors 20, 18
are engaged with each other at that location and the resulting
signal is carried to selected conductors 6, 8 in the tail portion
14. As shown in FIG. 1, the separator film 22 does not extend to
the edges 11, 13 of the films 10, 12 and the conductors 6, 8 do
extend to these edges.
Each connecting device 4 of the strip 2 has a W-shaped double crimp
portion at its upper end, the upper crimp portion comprising an
arcuate bight 32 having cantilever beams 34, 36 extending
therefrom. The end of the beam 34 is integral with a continuous
carrier strip 38 and the end of the beam 36 is connected by a sharp
reverse bend 46 to a beam 40 of the lower crimp portion. This lower
crimp portion has an arcuate bight 44 and a lower cantilever beam
42 from the end of which a contact pin or post 48 extends. This
integral pin has a reduced end 50 to facilitate its entry into a
connector header described below.
The beams 36, 40 are identified as cantilever beams notwithstanding
the fact that their ends are connected by the sharp reverse bend
46. This sharp reverse bend does not appear to affect the
functioning of the beams 40, 36 as cantilever beams, as will be
described below.
The spacing between adjacent connecting devices 4 on the strip 2 is
the same as the spacing between adjacent conductors 6, 8 on the
opposed surfaces of the film 10, 12. When a section of strip 4 is
positioned between films 10, 12, one of the beams of each
connecting device 4 will be in alignment with one or the other of
the conductors 6, 8. Thus, if the conductors are spaced apart on
each film by a distance 2D, the connecting devices should be spaced
apart by a distance D.
A section of the strip 2 is crimped onto the tail portion 14 of the
switch by crimping dies, as shown in FIG. 2 at 52, 52'. These
crimping dies are mirror images of each other and corresponding
structural features are therefore identified by the same reference
numerals differentiated by prime marks. The upper die 52 has a
front surface 54, a flat crimping surface 56 which extends inwardly
from the front surface, and a stop surface 58. The shoulder 60,
which is between the surfaces 56, 58, is recessed from the surface
54 by a distance such that the shoulder surface 60 does not engage
the bight portions 32 when the connecting devices are crimped. The
lower die 52' is normally spaced from the upper die, as shown in
FIG. 2, and during crimping the section of strip 2 onto the films,
the section of strip is positioned, as shown in FIG. 2, with the
carrier strip 38 adjacent to the surface 54 and with the pin
portions 48 extending downwardly adjacent to the surface 54'.
To crimp the section of strip 2 onto the films 10, 12, the end
portion of the tail of the switch is moved rightwardly from the
position of FIG. 2 so that the upper film 10 is between the beams
34, 36 and the film 12 is between the beams 40, 42 with the edges
11, 13 adjacent to the inner surfaces of the bights 32, 44 and with
the conductors 6, 8 each in alignment with one of the connecting
devices. Thereafter, the dies 52, 52' are moved towards each other
to their closed positions as shown in FIG. 3. The upper crimp
portion 34, 36 is crimped onto the upper film 10 and the lower
crimp portion 40, 42 is crimped onto the lower film 12. After the
dies are opened, the carrier strip 38 is removed, as shown in FIG.
4.
As will be explained below, the cantilever beams 34, 36, 40 and 42
are resiliently biased against the films after the crimping
operation has been carried out and have no tendency to move away
from the films from their positions shown in FIG. 4. Furthermore,
the crimping operation illustrated in FIGS. 2 and 3 does not result
in the imposition of extremely high compressive crimping forces on
the cantilever beams; the maximum crimping forces are rather
imposed only on the bight portions 32, 44 so that the possibility
of damage to the conductors 6, 8 is minimized.
If desired, the posts 48 can be connected to external conductors
directly as by soldering these posts to conductors on a circuit
board. In the disclosed embodiment, a molded housing 60, FIG. 5, is
provided for the crimped connecting devices and adjacent portions
of the films 10, 12. The housing 60 comprises a rectangular body 62
having an opening 64 extending into its underside and having an
upper surface 66. Pin receiving opening 68 extends through the body
62 from the upper surfaces 66 to the top wall 80 of the opening 64
so that upon downward movement of the tail portion 14 from the
position of FIG. 5, the film 12 will be on the surface 66 and the
post portions 48 of the connecting devices will extend through
openings 68 and will project downwardly from the surface 80.
Housing body 62 has an extension 70 projecting beyond the upper
surface 66 and the underside of this projection has spaced-apart
channels 72 extending thereacross which function as hinges. The
extension 70 can thus be folded, as shown in FIG. 7, so that the
portion 74 of the extension between the hinges 72 becomes a
sidewall of the housing and the portion 76 becomes a top wall with
the end portions of the films 10, 12 contained between this top
wall and the surface 66. Latch arms 78 are provided on the side
edges 77 of the extension which have hook ends that engage
shoulders in the endwall of the housing to hold the top wall
against the film 10.
The opening 64 is dimensioned to receive a header 82 (FIG. 7) of
the type containing contact terminals which receive the reduced
ends 50 of the terminal posts 48. The terminals in the header 82
extend through holes in the circuit board 30 and are soldered, as
shown at 84, to the conductors 26 on the underside of the circuit
board.
It is desirable to provide a strain relief means between the switch
and the housing 60. In the disclosed embodiment, integral pins 71
are provided on the upper surface 66 of the housing which are
received in holes 73 in the films 10, 12 so that when a tensile
force is applied to either the switch or the housing, the force
will be transmitted through the pins and openings and will not be
transmitted by the terminals.
The previously identified Application, Ser. No. 960,425 explains
the principles of crimped connections of the type preferred for the
instant invention and contains a detailed mathematical analysis
which permits the achievement of crimped connections having
pre-determined contact forces. Reference is made to this previously
identified application for such specific details, however, a
discussion is presented below, of the salient principles of the
crimped connection.
As illustrated in FIGS. 2 and 3, the cantilever beams of each crimp
portion are moved towards each other until each film 10, 12 is
gripped between the cantilever beams of one of the crimp portions.
Thereafter, the die surfaces 56, 56' are moved together an
additional distance further to flatten the crimp with accompanying
plastic deformation in the bight portions 32, 44. During this final
portion of the crimping operation, the cantilever beams of each
crimp portion of each terminal device are flexed so that they are
resiliently biased against the films, one crimp portion having its
beams bearing against one of the films. The cantilever beams of
each crimp portion are maintained in their flexed condition by the
plastically deformed bight portions 32 and 44 so that stable
electrical contact is maintained.
In order to achieve flexure of the cantilever beams of each crimp
portion of each terminal against the films, it is necessary to
dimension the connecting device such that during the final stages
of crimping, when the bight portions 32, 44 are plastically
deformed, the dies can travel the distance sufficient to accomplish
this plastic deformation of the bight portions. For example,
assuming that each crimp portion has an initial radius of curvature
R in its bight portion, a beam length L, a material thickness T,
and the material has given physical properties, such as strength
and elastic modulus, there is a crimp height (the distance between
the die surfaces 56, 56') which is reached at an intermediate stage
of the crimping operation and at which the ends of the cantilever
beams touch the surfaces of the film. It must be possible when this
intermediate stage is reached to further crimp the connecting
devices so that the beams will be flexed against the surfaces of
the film thereby to establish electrical contact in accordance with
the invention of the above identified Application Ser. No. 960,425.
The material of the terminals must be such that it is capable of
undergoing the substantial amount of plastic deformation in the
bight portions 32, 44 during this final stage of crimping and the
initial radius of curvature R must be such that the terminals can
be crimped through this final stage of crimping.
Connecting devices, in accordance with the invention, can be made
of any desired size and of many different materials. For example,
good results have been obtained by forming the terminals of 0.012"
thick brass with the length of the cantilever beams being about
0.080" and the radius of curvature of both bight portions being
about 0.020".
If desired, slight projections can be provided on the internal
surfaces of the cantilever beams to penetrate a thin film on the
conductors and/or to stabilize the terminals, after crimping,
against lateral movement relative to the films. In other words,
connecting devices in accordance with the invention, can have
insulation penetrating means in combination with the resiliently
biased and flexed cantilever beams for establishing contact.
* * * * *